Hot cell examination table

ABSTRACT

A table for use in a hot cell or similar controlled environment for use in examining specimens. The table has a movable table top that can be moved relative to a table frame. A shaft is fixedly mounted to the frame for axial rotation. A shaft traveler having a plurality of tilted rollers biased against the shaft is connected to the table top such that rotation of the shaft causes the shaft traveler to roll along the shaft. An electromagnetic drive is connected to the shaft and the frame for controllably rotating the shaft.

The Government has rights in this invention pursuant to Contract No.N00024-79C-4026 awarded by the U.S. Department of Energy.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to tables for use in examination procedures and,more particularly, to a table having a movable table top.

2. Prior Art

To perform photographic, microscopic, photomicrographic and visualexamination on small parts and components, especially specimens that maybe radioactive, it is customary to execute these operations in acontrolled environment. One such controlled environment for radioactivespecimens is called a hot cell. The hot cell often has appropriateoptical apparati that protrude through the protective walls of the hotcell. In order to manipulate the specimen or object under the opticalviewer, remotely controlled stages are used to move the object.

It is also known to use tilted rollers biased against a rotatable shaftsuch that when the shaft is rotated, the biased tilted rollersfrictionally roll along the shaft to move an article connected to therollers.

It is an objective of the present invention to provide an examinationtable with a movable table top with minimal maintenance requirements foruse in a hostile environment.

It is another objective of the present invention to provide anexamination table with a movable table top having an overdrivecapability to eliminate safety limit switches for the bounds of thetable top travel.

It is another objective of the present invention to provide anexamination table with a movable table top having a removable drivemodule with a minimum number of fasteners for readily removing andreplacing the drive module using remote handling means such asmanipulators, etc.

SUMMARY OF THE INVENTION

The foregoing problems are overcome and other advantages are provided byan examination table having a movable table top.

In accordance with one embodiment of the invention the table has aframe, a movable table top and means for controllably moving the tabletop relative to the frame. The moving means comprises shaft means, drivemeans and shaft travel means. The shaft means is fixedly mounted to theframe for axial rotation. The drive means is connected to the frame andshaft means for rotating the shaft means. The shaft travel meanscomprises a plurality of tilted rollers, means for biasing the tiltedrollers against the shaft means and means for connecting the shafttravel means to the table top such that rotation of the shaft meanscauses the tilted rollers to frictionally roll along the shaft meanswhereby the table top is moved parallel to the shaft means as the shaftmeans is rotated.

In accordance with another embodiment of the invention, the table has atable top moving means comprising a shaft means, drive means and asingle fastener. The shaft means is mounted to the frame for axialrotation and has a central aperture and a first gear at one end. Thedrive means is provided for rotating the shaft means and has a motormeans, a drive shaft and a pinion gear means. The drive shaft has asecond gear and is insertable into the shaft means central aperture withthe pinion gear means connecting the first and second gears. The singlefastener is provided for mounting the drive means to the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the invention are explainedin the following description, taken in connection with the accompanyingdrawings wherein:

FIG. 1 is a schematic perspective view of a hot cell examination tableincorporating features of the invention.

FIG. 2 is a schematic partial cross-sectional view of a drive module.

FIG. 3 is a schematic view of a shaft travel mechanism of the tableshown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, there is shown one embodiment of an examinationtable 2 incorporating features of the present invention. The table 2 isgenerally used to perform photographic, microscopic, photomicrographicand visual examination on small parts and components such as radioactiveparts and components in a radioactive hot cell (not shown). The hot cellwould of course have appropriate optical apparati that would protrudethrough the protective walls of the hot cell. In order to manipulate thesmall part, component or object under the optical apparati, the table 2is capable of moving the object relative to the optical apparati viaremote controlled stages as will be described below.

The table 2, in this embodiment, generally comprises a first framemember 4, a second frame member 6, a third frame member 8 and a tabletop assembly 10. The table 2 also generally comprises a base 12 which isintended to be relatively stationarily positioned in the hot cell (notshown). The first frame member 4 is generally fixedly connected to thebase 12 and, in the embodiment shown, extends vertically upward in the Ydirection. In this embodiment, the first frame member 4 generallycomprises two vertically extending bars or shafts 14 and 15 which areboth fixedly mounted to the first frame member 4. However, the firstshaft 14, in the embodiment shown, is also rotatably mounted with thefirst frame member 4 for axial rotation about its center axis. Mountedon top of the first frame member 4, in the embodiment shown, is anelectromechanical drive module 16. The drive module 16 generallycomprises a frame 18, a fastener 20, a drive motor 22 and an electricalconduit 24 for supplying power to the drive motor 22 and which can alsobe used for transmitting signals from a computer and/or control panel(not shown) located outside of the hot cell.

The second frame member 6 is generally provided for movement in thevertical Y direction along the first and second shafts 14 and 15 of thefirst frame member 4. The second frame member 6 generally has twohorizontal bars or shafts 26 and 27 positioned along the X axis whichare both fixedly mounted with the second frame member 6. However, thethird shaft 26 is also mounted for axial rotation along its center axis.Mounted on the side of the second frame member 6 is a secondelectromechanical drive module 28 which is substantially identical tothe first electromechanical drive module 16 and thus, like numbers areused to identify similar parts. The second frame member 6, in theembodiment shown, also comprises two shaft travel mechanisms 30 and 31which are fixedly connected to the second frame member 6. The firsttravel shaft mechanism 30 has the first shaft 14 of the first framemember 4 passing therethrough. As will be described below, the firstshaft travel mechanism 30, when the first shaft 14 is rotated, iscapable of moving the second frame member 6, the third frame member 8and the table top assembly 10 up and down in the vertical Y directiondepending upon the direction of rotation of the first shaft 14. Thesecond shaft travel mechanism 31 generally has the second shaft 15 ofthe first frame member 4 passing therethrough. Suitable means areprovided in the second travel mechanism 31, such as a bearing means,that allows the second shaft travel mechanism 31 to move relativelyfreely up and down the shaft 15 while also providing movement stabilityof the second frame member 6 as it moves up and down along the first andsecond shaft 14 and 15 as generally indicated by the arrow A.

The third frame member 8 is generally provided for movement in thehorizontal X direction. Connected to the frame 8, in the embodimentshown, are a fifth shaft 32, a sixth shaft 33, a third shaft travelmechanism 34, a fourth shaft travel mechanism 35 and a frame extension36. The third shaft travel mechanism 34 and the fourth shaft travelmechanism 35 are substantially identical to the first and second shafttravel mechanisms 30 and 31, respectively. With the axial rotation ofshaft 26, the third shaft travel mechanism 34 is capable of moving thethird frame 8 and the table top assembly 10 in the horizontal Xdirection as indicated by arrow B depending upon the direction ofrotation of the third shaft 26. The fourth shaft travel mechanism 35 issubstantially identical to the second shaft travel mechanism 31 in thatsuitable means are provided (not shown) such that as the frame 8 movesalong the shafts 26 and 27 the fourth shaft travel mechanism 35 allowsthe frame 8 to move relatively freely along the fourth shaft 27 whilealso providing stability to the cantilevered table top assembly 10. Theframe extension 36 generally extends from the third frame member 8 inthe Z direction and has an end plate 38 which has a thirdelectromechanical drive module 40 mounted thereto. In the embodimentshown, the third electromechanical drive module 40 is substantiallyidentical to the first and second electromechanical drive modules 16 and28, therefore, like numbers are used to represent like parts. The sixthshaft 33 is generally fixedly mounted with the third frame member 8. Thefifth shaft 32 is generally mounted to the third frame member 8 and theend plate 38 for axial rotation therebetween. The table top assembly 10is generally connected to the fifth and sixth shafts 32 and 33 via afifth shaft travel mechanism 42 and a sixth shaft travel mechanism 43.The fifth travel mechanism 42 is substantially identical to the firstand third shaft travel mechanism 30 and 34. The table top assembly 10generally also comprises a table top member 44, a frame 46, a rotationmechanism 48 and a tilt mechanism 50. The frame 46 is connected to thefifth and sixth shaft travel mechanisms 42 and 43 such that rotation ofthe fifth shaft 32 results in movement of the table top assembly 10 inthe Z direction indicated by arrow C. The rotation mechanism 48generally comprises a fourth electromechanical drive module 52 which issubstantially identical to the other electromechanical drive modules ofthe table. The fourth electromechanical drive module 52 allows the tabletop member 44 to rotate as indicated by arrow D. The tilt mechanism 50generally comprises a fifth electromechanical drive mechanism 54 havinga gear 56 that can move a tilt member 58 which is connected to the frame46 for tilting the frame 46 and thus tilting the table top member 44 asindicated by arrow E.

Referring now to FIG. 2, one embodiment of an electromechanical drivemodule is shown. As described above, the first, second, third, fourthand fifth drive modules 16, 28, 40, 52 and 54 are substantiallyidentical to each other. Each module comprises a frame 18, a fastener20, a drive motor 22 and an electrical conduit 24. In the embodimentshown in FIG. 2 the drive module 60 also comprises a potentiometer 62 todetect turns within the module 60. The fastener 20, in the embodimentshown, generally comprises a fastener head 64, a shaft 66 and a spring68. The shaft 66 has a first end 70 with threads thereon to engage athreaded hole 72 located in each of the first frame member 4, secondframe member 6, end plate 38, table top frame 46 and sixth shaft travelmechanism 43. The module frame 18 comprises an aperture 75 for passageof the shaft 66 therethrough. The aperture 75 also includes an enlargedaperture portion 76. A clip 74 is attached to the shaft 66 proximate thethreaded portion 70 and prevents the shaft 66 from being removed fromthe aperture 75 while also allowing limited movement within the aperture75 when the module 60 is not attached to the table 2. The fastener head64 generally comprises a receiving aperture 79 for receiving a secondend 82 of the shaft 66. A pin 78 fixedly attaches the fastener head 64to the second end 82 of the shaft. The fastener head 64 also comprisesan enlarged portion 80 of the receiving aperture 79 which has the spring68 at least partially contained therein, the spring being compressedbetween the fastener head 64 and the module frame 18. The spring loadedfastener 20 allows for easy mounting and dismounting of the module 60such that the threaded end 70 of the shaft 66 does not interfere withpositioning of the module 60 on the table 2 and also allows for quickremoval of the module 60 when the threaded end 70 of the shaft 66 isunthreaded from the threaded hole 72.

In the embodiment shown in FIG. 2 a shaft 84 is shown which is rotatablymounted in a frame 86 for axial rotation. The shaft 84 generallysymbolizes either the first shaft 14, third shaft 26, fifth shaft 32, ashaft extending between the table top member 44 into the frame 46 or ashaft extending from the gear 56 into the sixth travel mechanism 43. Theframe 86 is generally intended to symbolize either the first framemember 4, second frame member 6, end plate 38, table top frame 46 orsixth shaft travel mechanism 43. In the embodiment shown in FIG. 2,suitable bearing means 88 are provided such that the shaft 84 can rotatewithin the frame 86. The end 90 of the shaft 84, in this embodiment,extends past the frame 86 into a central aperture 91 of a matingco-axial shaft 92 extending from the drive motor 22. In an alternateembodiment of the invention, the shaft 92 may extend into a centralaperture of the shaft 84. The end of the shaft 84 also comprises a gear94 fixedly connected thereto. The mating shaft 92 extending from thedrive motor 22 also comprises a gear 96 fixedly connected thereto. Boththe gears 94 and 96 of the mating shaft 92 and the shaft 84, in theembodiment shown, have identical gear sizes thereon. The shaft end 90 ofshaft 84 and the central aperture 91 have a circular cross-section suchthat the two shafts 84 and 92 can be mated at any desired orientation.However, the actual power coupling between the shaft 92 and shaft 84 isaccomplished with an idler pinion gear 98 connecting the two gears 94and 96. The modular frame 18 has a suitable aperture for positioning ofthe shafts and gears therein. In attaching the module 60 to the shaft 84and frame 86, once the two shafts 84 and 92 are inserted into each otheras male and female, the only degree of freedom left is rotational, whichdoes not effect the meshing of the gear transmission. The singlefastener 20 in addition to holding the module 60 to its base or frame 86is able to restrict this rotation freedom of movement. Thus, when themodule 60 is connected to the frame 86 rotation of the shaft 92 by thedrive motor 22 can cause the shaft 84 to rotate axially.

Referring now also to FIG. 3, there is shown a schematic view of theshaft travel mechanisms contained in the first travel mechanism 30,third travel mechanism 34 and fifth travel mechanism 42. The shafttravel mechanism 99 shown in FIG. 3 generally comprises a frame 104,tilted rollers 100 and springs 102. The shaft 84 is located between thetilted rollers 100 and makes frictional contact therewith. The tiltedrollers 100 are biased against the shaft 84 by springs 102. The frame104 provides a support for the springs 102 and contain the tiltedrollers 100 and springs 102 within the shaft travel mechanism 99. Inoperation, when the shaft 84 is axially rotated in a clockwise directionas indicated by arrow F, the shaft travel mechanism 99 is frictionallymoved along the shaft 84 in the direction indicated by arrow G. When theshaft 84 is axially rotated in the counter clockwise direction asindicated by arrow H the shaft travel mechanism 99 will be moved alongthe shaft 84 in the direction of the arrow I. Thus, the actualtranslation of the power supplied by shaft 92 to the movement of a framemember along a shaft 84 is accomplished with the relatively smooth shaft84 rotating between the tilted rollers 100 that are spring loadedagainst it. The unique nature of this application is having no drivescrew, its maintenance in a hostile environment is greatly eased.Furthermore, having a natural overdrive capability, the tilted rollers100 will simply start to slip on the shaft 84 when the translationalresistance exceeds a set value. This allows the elimination for the needof separate safety limit switches on both ends of the travel of theshaft 84.

A major requirement for equipment working in hostile environments is theease of replacement of electrical components that tend to fail morefrequently, and the ability to accomplish this replacement with remotemeans such as manipulators. Minimizing the number of fasteners, andarranging them into accessible patterns is imperative. Since visibilityis also a problem it is necessary to insure that insertion of a moduleinto a position is to be done without the need for viewing smallfeatures and handling small components. The electromechanical drivemodule described above fully meets these requirements. Another featureof the present invention is the combined use of the smooth shafttranslator with a single home position sensor on one end of the travelof the translator in conjunction with a computer to provide intelligenceto gain and retain absolute position control along the shaft travel.Another feature of the present invention is the disconnectable ordemountable combined drive/sensor module that lends itself well forremote maintenance or replacement. In this solution, all electrical andelectromechanical parts are combined into one module. Another feature ofthe present invention is the coupling and alignment method between thedemountable drive/sensor module and the drive member which uniquelylends itself to remote handling while insuring critical alignment ofrotating components without need for sensitive adjustments. Stillanother feature of the present invention is the use of single turnpotentiometers to detect multi turn movements within the module andlogically scrutinizing the output in software to define multi countingof cycle turns.

It should be understood that the foregoing description is onlyillustrative of the invention. Various alternatives and modificationscan be devised by those skilled in the art without departing from thespirit of the invention. Accordingly, the present invention is intendedto embrace all such alternatives, modifications and variances which fallwithin the scope of the appended claims.

What is claimed is:
 1. An examination table for use in a hostileenvironment having a frame, a movable table top, and means forcontrollably moving said table top relative to said frame, said movingmeans comprising:shaft means fixedly mounted to said frame for axialrotation; electromechanical drive means connected to said frame and saidshaft means for rotating said shaft means; and shaft travel means fortraveling along said shaft means, said shaft travel means comprising aplurality of tilted rollers, means for biasing said tilted rollersagainst said shaft means and means for connecting said shaft travelmeans to said table top such that rotation of said shaft means causessaid tilted rollers to frictionally roll along said shaft means wherebysaid table top is moved parallel to said shaft means as said shaft meansis rotated.
 2. A table as in claim 1 wherein said shaft means comprisesat least three shafts, each shaft oriented in a different plane.
 3. Atable as in claim 1 further comprising means for rotating said table toprelative to said frame.
 4. A table as in claim 3 further comprisingmeans for tilting said table top relative to said frame.
 5. A table asin claim 1 wherein said drive means comprises a shaft with a gear endfor coaxial coupling with a gear end of said shaft means.
 6. A table asin claim 5 wherein said drive means further comprises an idler piniongear coupling said drive means shaft with said shaft means.
 7. A tableas in claim 6 further comprising a single fastener for mounting saiddrive means to said frame whereby said coaxial coupling of said drivemeans shaft and said shaft means, and said single fastener allows easyreplacement of said drive means by use of a remote means.
 8. A table asin claim further comprising sensor means to sense the position of saidshaft travel means on said shaft means.
 9. A table as in claim 8 furthercomprising computer means for processing information from said sensormeans to gain and retain position control of said shaft travel meansalong said shaft means.
 10. A table as in claim 8 wherein said sensormeans and said drive means are contained in a module which isdisconnectably mounted to said frame and said shaft means.
 11. A tableas in claim 10 further comprising single turn potentiometer means todetect multiple turn movements within said module.
 12. An examinationtable having a frame, a movable table top, and means for controllablymoving said table top relative to said frame, said moving meanscomprising:shaft means mounted to said frame for axial rotation, saidshaft means having a first end extending past said frame and a firstgear at said first end; drive means for rotating said shaft means, saiddrive means having a motor means, a drive shaft, a pinion gear means anda second gear, said drive shaft having a central aperture for at leastpartially receiving said shaft means first end with said pinion gearmeans connecting said first and second gears; and a single fastener formounting said drive means to said frame.